Of all high-temperature materials, nickel-based superalloys have the most favorable combination of mechanical properties, resistance to corrosion and processability for gas turbine construction for aircraft and power plants. The considerable increase in strength is made possible in particular by the particle hardening with very high proportions by volume of the coherent γ′ phase Ni3(Al—Ti, Ta, Nb). However, in general alloys with a higher γ′ content can only be considered weldable to a limited extent. This poor weldability is caused by:                a) Nickel alloys generally have a relatively low thermal conductivity and a relatively high coefficient of thermal expansion, similar to the values of austenitic steels and Co alloys. The welding heat which is introduced is therefore dissipated comparatively slowly, and the inhomogeneous heating leads to high thermal stresses, causing thermal fatigue which can only be dealt with at considerable effort.        b) Nickel alloys are very sensitive to hot cracks in the event of a rapid change in the temperature cycles within the high temperature range. The cause is grain boundary fusion resulting from fluctuations in the chemical composition (segregations) or the formation of low-melting phases, such as sulfides or borides.        c) Nickel alloys generally have a high proportion of the γ′ phase in a γ matrix. In the case of nickel-based superalloys for turbine components, the γ′ phase amounts to greater than 40 vol %. This achieves a high strength but also leads to a low ductility of the material, in particular at low temperatures and in the range of the temperature field in which the γ/γ′ precipitation phenomenon may occur (“ductility-dip temperature range”, also known as the “subsolidus ductility dip”, approximately 700° C. to 1100° C., depending on the alloy). Consequently, stresses which occur can less readily be absorbed through plastic flow, which generally increases the risk of crack formation.        d) Nickel alloys exhibit the phenomenon of post-weld heat treatment cracks, also known as strain-age cracking. In this case, cracks are produced in a characteristic way in the first heat treatment following the weld as a result of γ/γ′ precipitation phenomena in the heat-affected zone or—if the weld filler can form the γ′ phase—also in the weld metal. This is caused by local stresses which form during the precipitation of the γ′ phase as a result of the contraction of the surrounding matrix. The susceptibility to strain-age cracking increases with an increasing level of γ′-forming alloy constituents, such as Al and Ti, since this also increases the proportion of γ′ phase in the microstructure.        
If welds in which the base metal and the filler are identical are attempted at room temperature using conventional welding processes, for many industrial Ni-based superalloys for turbine laser vanes (e.g. IN738LC, Rene80, IN939), it is not currently possible to avoid the formation of cracks in the heat-affected zone and in the weld metal.
At present, a number of processes and process steps are known to improve the weldability of nickel-based superalloys:                a) Welding with preheating:        
One way of avoiding cracks when welding nickel-based superalloys using high-strength fillers (likewise nickel-based superalloys) is to reduce the temperature difference and therefore the stress gradient between weld joint and the remainder of the component. This is achieved by preheating the component during the welding. One example is manual TIG welding in a shield and gas box, with the weld joint being preheated inductively (by means of induction coils) to temperatures of greater than 900° C. However, this makes the welding process significantly more complicated and expensive. Moreover, on account of inaccessibility, this cannot be implemented for all regions which are to be welded.                b) Welding with extremely little introduction of heat:        
This involves the use of welding processes which ensure that very little heat is introduced into the base metal. These processes include laser welding and electron beam welding. Both processes are very expensive. Moreover, they require outlay on programming and automation, which may be uneconomical for repair welds, with frequently fluctuating damage patterns and locations.
US 2004/0115086 A1 has disclosed a nickel alloy with various additions.